The overall objective of our research program is an increased understanding of the active and inactive states of the eukaryotic genome. As a working hypothesis it is assumed that gene expression in the eukaryote is critically affected by the type and form of other macromulecules associated with the DNA, particularly the nonhistone chromosomal proteins (NHC proteins). As part of a program to study the roles of the various NHC proteins of Drosophila we will attempt to use a "reconstitution" procedure to bind specific NHC proteins in complexes with histones and specific segments of Drosophila DNA, the latter obtained as cloned plasmids. The success of this approach will be assayed by using an immunofluorescent technique to determine whether or not NHC proteins so isolated are indeed associated with these DNA sequences in vivo in polytene chromosomes. Subsequently, the transcription properties of the reconstituted "plasmid chromatin" will be analyzed using purified Drosophila RNA polymerases. The ability to work in vitro with a small, defined chromatin template would be extremely valuable in studies of the control of gene transcription in eukaryotes.